1. Field of Invention
The present invention is directed to compositions of matter and to processes for producing the compositions of matter. More specifically, the present invention is directed to processes of making compositions of matter which are useful in the lubrication of various plastic extrusions. One process involves the production of specified fatty acid metal salts in situ in the presence of selected polar substances during the preparation of the composition. Hydrocarbon waxes (polyethylene waxes, microwaxes, paraffins and/or alpha-olefins) are added to the composition to produce a suitable lubricant composition. Another process of the present invention involves preparation of the composition by combining predetermined amounts of one or more specified fatty acid metal salts, selected polar alcohols and optionally small amounts of a fatty acid, polyethylene waxes, microwaxes, paraffins and/or alpha-olefins. Both processes of the present invention yield compositions which may be added to plastic extrusion materials to enhance the lubricity thereof during extrusion. The compositions of matter of this invention are especially useful for those plastics requiring addition of lubricants to render them processable, such as polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), polyvinylidene chloride (PVDC) and copolymers thereto.
2. Prior Art Statement
PVC compositions and other thermoplastic extrusion compositions have been advantageously extruded with various types of extrusion aids (microingredients) which are well known in the art. One type of well known extrusion aid (extrusion lubricant composition) contains paraffinic hydrocarbon waxes admixed with calcium salts of specific fatty acids such as calcium stearate. These additives are customarily preblended with thermoplastic extrusion compositions, such as PVC resin, prior to extrusion. To facilitate blending, it is preferable that the additives be in a solid free-flowing form as either flakes, granules, powders or prills. Solids in any of these forms are easier to weigh out and transfer to the mixer for each batch blended. It is also desirable to combine various components into one product in order to reduce the number of weighings required for each batch of thermoplastic resin blended. The paraffinic and polyethylene waxes can be melted together and flaked, granulated, prilled or powdered. The calcium stearate component, however, is not compatible with the waxes and cannot be simply blended together. The calcium stearate is commonly supplied as a powder. Physically blending the calcium stearate with a wax in powder form would result in separation of the two during handling because of differences in particle size and density.
Calcium stearate can be made compatible in paraffinic waxes by heating to temperatures in excess of 150.degree. C. as taught in Conoco's U.S. Pat. No. 3,883,362; 3,883,363; 3,979,345; 3,986,995 and 4,248,747. As taught therein, the calcium stearate may be an initial component or may be formed in situ. A uniform friable melt is obtained whether or not the calcium stearate is formed in situ rendering a partial solution to the problem. The disadvantages of these methods include the high temperatures needed which can not be readily achieved by conventional steam heating except through high pressure lines, electrical heaters, or oil heat exchangers, which are not available to many processors and result in high energy consumption. Another disadvantage which occurs, even when the calcium stearate is formed in situ by these prior art methods, is the high viscosity which results when the calcium stearate goes into the wax, making the processing and handling of the finished product difficult.
Another procedure for incorporating calcium stearate into paraffinic waxes involves the precipitation thereof from water, as described in Malinckrodt's U.S. Pat. No. 3,909,472. This method has disadvantages in that excess handling is required and high energy consumption occurs. The waxes and free acid are melted in a kettle and transferred to a separate kettle containing the water/calcium base slurry. Excess energy is consumed in heating the water and in drying the precipitated product. This basic procedure is likewise utilized for the production of pure calcium stearate (no wax used) in the Norac U.S. Pat. No. 3,803,188, and lead stearates in U.S. Pat. No. 2,650,932.
In yet other methods, an aqueous dispersion can be prepared as described by American Hoechst Corporation's U.S. Pat. Nos. 4,040,996 and 4,040,997, for example. However, such dispersions have the disadvantages of longterm unstability, high shipping costs if water dispersion is shipped, and complicated production procedures and high energy consumption if the product is coated on a filler and dried.